C_(50)(D_(5h))衍生物-异质富勒烯C_(48)P_2的分子行为理论研究  

Theoretical Studies on Molecular Behavior of C_(50)(D_(5h)) Derivative:Heterofullerene C_(48)P_2

作　　者：许秀芳[1] 尚贞锋[1] 李瑞芳[1] 赵学庄[1] 

机构地区：[1]南开大学化学系,天津300071

出　　处：《高等学校化学学报》2009年第6期1219-1226,共8页Chemical Journal of Chinese Universities

基　　金：国家"九七三"计划(批准号:2006CB932900)资助

摘　　要：用半经验的AM1和MNDO方法以及密度泛函B3LYP/3-21G方法对C50(D5h)的衍生物C48P2的所有可能的异构体进行了系统的理论研究.优化了稳定构型,计算了生成热、HOMO-LUMO能级差、NICS值、红外光谱及电子光谱,并与C48X2(X=B,N)的分子行为进行了比较.计算结果表明:(1)C48P2的最稳定异构体是异构体C48P2-78,该异构体对应于赤道位置六元环内的1,4-取代产物;(2)决定C48P2异构体稳定性的主要因素是碳笼的张力,而稳定性和芳香性之间没有明显的相关性;(3)相对较稳定的C48P2异构体的HOMO-LUMO能级差比C50的HOMO-LUMO能级差大;(4)计算出的红外光谱以及电子光谱可以供实验参考;计算出的NICS值也可以用来表征C48P2各异构体.(5)C48P2与C48X2(X=B,N)具有相同的取代选择性规律及稳定性决定因素,并且相对较稳定的异构体均具有比C50本体大的HOMO-LUMO能级差.A systematic investigation on all possible P-doped C50 （D5h） isomers C48 P2 was performed using the semiempirieal methods AM1 and MNDO and density functional theory method B3LYP/3-21 G. The equilibrium geometrical structures, heats of formation, HOMO-LUMO energy gaps, aromaticity, infrared vibrational spectrum and electronic absorption spectrum were studied. Further, the molecular behavior was compared with those of C48X2 （X = B, N）. The results indicate that： （1） the isomer C48P2-78, which corresponds to 1,4-substitution in the six-membered ring located on the equator, is the most stable isomer for C48P2- （2） The driving force governing the stabilities of the present studied C48P2 isomers is the strain being inherent in the C50 cage, while the stability doesn＇t correlate with the aromatieity. （3） The more stable C48P2 isomers have larger HOMO-LUMO energy gap compared with C50. （4） The vibrational spectra and electronic absorption spectra of these substituted fullerenes have been calculated, which could serve as a framework to interpret future experimental results. The computed nucleus independent chemical shifts（NICS） values also provide a basis for the possible characterization of these C48P2 isomers. （5） C48P2 and C48X2 （X = B, N） have the same rule of doping and governing force of stability, and larger HOMO-LUMO energy gap compared with C50.

关 键 词：异质富勒烯 几何结构 稳定性 光谱 

分 类 号：O641[理学—物理化学]